The association between sleep and cognitive abnormalities in bipolar disorder.

BACKGROUND: Bipolar disorder (BD) is associated with attentional and processing abnormalities. Such abnormalities are also seen in healthy subjects with sleep disruption. We hypothesised cognitive abnormalities in BD patients would be worse in those with objectively verified sleep abnormalities. METHODS: Forty-six BD patients and 42 controls had comprehensive sleep/circadian rhythm assessment over 21 days alongside mood questionnaires. Cognitive function was assessed with a range of tasks including Psychomotor Vigilance Test (PVT), Attention Network Task (ANT) and Digit Symbol Substitution Test (DSST). BD participants with normal and abnormal sleep were compared with age- and sex-matched controls. RESULTS: BD patients had longer response times and made more lapses (responses >500 ms) than controls on the PVT (both p < 0.001). However, patients with normal sleep patterns did not differ from controls while those with sleep abnormalities did (p < 0.001). An identical pattern of effects were seen with the ANT response times, with the abnormality in bipolar abnormal sleepers related to the executive attentional network. Similarly, patients made fewer correct responses on the DSST compared with the controls (p < 0.001). Bipolar normal sleepers did not differ while those with abnormal sleep did (p < 0.001). All these differences were seen in bipolar abnormal sleepers who were euthymic (p < 0.01) and across the main abnormal sleep phenotypes. CONCLUSIONS: We confirm impairment in attention and processing speed in BD. Rather than sleep abnormalities exacerbating such dysfunction, the impairments were confined to bipolar abnormal sleepers, consistent with sleep disturbance being the main driver of cognitive dysfunction.

Multiple-therapy-resistant major depressive disorder: a clinically important concept.

Many novel therapeutic options for depression exist that are either not mentioned in clinical guidelines or recommended only for use in highly specialist services. The challenge faced by clinicians is when it might be appropriate to consider such 'non-standard' interventions. This analysis proposes a framework to aid this decision.Declaration of interestIn the past 3 years R.H.M.W. has received support for research, expenses to attend conferences and fees for lecturing and consultancy work (including attending advisory boards) from various pharmaceutical companies including Astra Zeneca, Cyberonics, Eli Lilly, Janssen, LivaNova, Lundbeck, MyTomorrows, Otsuka, Pfizer, Roche, Servier, SPIMACO and Sunovion. D.M.B.C. has received fees from LivaNova for attending an advisory board. In the past 3 years A.J.C. has received fees for lecturing from Astra Zeneca and Lundbeck; fees for consulting from LivaNova, Janssen and Allergan; and research grant support from Lundbeck.In the past 3 years A.C. has received fees for lecturing from pharmaceutical companies namely Lundbeck and Sunovion. In the past 3 years A.L.M. has received support for attending seminars and fees for consultancy work (including advisory board) from Medtronic Inc and LivaNova. R.M. holds joint research grants with a number of digital companies that investigate devices for depression including Alpha-stim, Big White Wall, P1vital, Intel, Johnson and Johnson and Lundbeck through his mindTech and CLAHRC EM roles. M.S. is an associate at Blueriver Consulting providing intelligence to NHS organisations, pharmaceutical and devices companies. He has received honoraria for presentations and advisory boards with Lundbeck, Eli Lilly, URGO, AstraZeneca, Phillips and Sanofi and holds shares in Johnson and Johnson. In the past 3 years P.R.A.S. has received support for research, expenses to attend conferences and fees for lecturing and consultancy work (including attending an advisory board) from life sciences companies including Corcept Therapeutics, Indivior and LivaNova. In the past 3 years P.S.T. has received consultancy fees as an advisory board member from the following companies: Galen Limited, Sunovion Pharmaceuticals Europe Ltd, myTomorrows and LivaNova. A.H.Y. has undertaken paid lectures and advisory boards for all major pharmaceutical companies with drugs used in affective and related disorders and LivaNova. He has received funding for investigator initiated studies from AstraZeneca, Eli Lilly, Lundbeck and Wyeth.

Study protocol for a randomised pragmatic trial comparing the clinical and cost effectiveness of lithium and quetiapine augmentation in treatment resistant depression (the LQD study).

BACKGROUND: Approximately 30-50% of patients with major depressive disorder can be classed as treatment resistant, widely defined as a failure to respond to two or more adequate trials of antidepressants in the current episode. Treatment resistant depression is associated with a poorer prognosis and higher mortality rates. One treatment option is to augment an existing antidepressant with a second agent. Lithium and the atypical antipsychotic quetiapine are two such add-on therapies and are currently recommended as first line options for treatment resistant depression. However, whilst neither treatment has been established as superior to the other in short-term studies, they have yet to be compared head-to-head in longer term studies, or with a superiority design in this patient group. METHODS: The Lithium versus Quetiapine in Depression (LQD) study is a parallel group, multi-centre, pragmatic, open-label, patient randomised clinical trial designed to address this gap in knowledge. The study will compare the clinical and cost effectiveness of the decision to prescribe lithium or quetiapine add-on therapy to antidepressant medication for patients with treatment resistant depression. Patients will be randomised 1:1 and followed up over 12 months, with the hypothesis being that quetiapine will be superior to lithium. The primary outcomes will be: (1) time to all-cause treatment discontinuation over one year, and (2) self-rated depression symptoms rated weekly for one year via the Quick Inventory of Depressive Symptomatology. Other outcomes will include between group differences in response and remission rates, quality of life, social functioning, cost-effectiveness and the frequency of serious adverse events and side effects. DISCUSSION: The trial aims to help shape the treatment pathway for patients with treatment resistant depression, by determining whether the decision to prescribe quetiapine is superior to lithium. Strengths of the study include its pragmatic superiority design, broad inclusion criteria (external validity) and longer follow up than previous studies. TRIAL REGISTRATION: ISRCTN registry: ISRCTN16387615 , registered 28 February 2016. ClinicalTrials.gov: NCT03004521 , registered 17 November 2016.

Altered hippocampal function in major depression despite intact structure and resting perfusion.

BACKGROUND: Hippocampal volume reductions in major depression have been frequently reported. However, evidence for functional abnormalities in the same region in depression has been less clear. We investigated hippocampal function in depression using functional magnetic resonance imaging (fMRI) and neuropsychological tasks tapping spatial memory function, with complementing measures of hippocampal volume and resting blood flow to aid interpretation. METHOD: A total of 20 patients with major depressive disorder (MDD) and a matched group of 20 healthy individuals participated. Participants underwent multimodal magnetic resonance imaging (MRI): fMRI during a spatial memory task, and structural MRI and resting blood flow measurements of the hippocampal region using arterial spin labelling. An offline battery of neuropsychological tests, including several measures of spatial memory, was also completed. RESULTS: The fMRI analysis showed significant group differences in bilateral anterior regions of the hippocampus. While control participants showed task-dependent differences in blood oxygen level-dependent (BOLD) signal, depressed patients did not. No group differences were detected with regard to hippocampal volume or resting blood flow. Patients showed reduced performance in several offline neuropsychological measures. All group differences were independent of differences in hippocampal volume and hippocampal blood flow. CONCLUSIONS: Functional abnormalities of the hippocampus can be observed in patients with MDD even when the volume and resting perfusion in the same region appear normal. This suggests that changes in hippocampal function can be observed independently of structural abnormalities of the hippocampus in depression.

The interrelationship between attentional and executive deficits in major depressive disorder.

OBJECTIVE: Cognitive dysfunction is an established feature of major depressive disorder (MDD). However, it remains unclear whether deficits in different cognitive domains are relatively independent or originate from a circumscribed 'primary deficit'. This study tested the hypothesis that a deficit in attention represents a primary deficit in depression. METHOD: Neuropsychological function was assessed in 30 depressed patients with MDD and 34 control participants. Cognitive composites were derived from a minimum of three tests and included attention, executive function, visuospatial memory and verbal memory. A multivariate analysis of variance was used to assess group differences in overall cognitive performance, and multiple regression models were used to evaluate the role of attention in deficits in other domains. RESULTS: The cognitive deficit in the depressed sample was found to be characterized by poorer performance in attention and executive function. When evaluating the interrelationship between the two deficits, the attentional deficit was found to persist when variability in executive function was statistically accounted for, whilst the executive deficit was eliminated when attention was accounted for. CONCLUSION: The results demonstrated that the attentional deficit could not be explained by deficits in executive function, which provides support for a primary attention deficit in depression.

Early life trauma, depression and the glucocorticoid receptor gene--an epigenetic perspective.

BACKGROUND: Hopes to identify genetic susceptibility loci accounting for the heritability seen in unipolar depression have not been fully realized. Family history remains the 'gold standard' for both risk stratification and prognosis in complex phenotypes such as depression. Meanwhile, the physiological mechanisms underlying life-event triggers for depression remain opaque. Epigenetics, comprising heritable changes in gene expression other than alterations of the nucleotide sequence, may offer a way to deepen our understanding of the aetiology and pathophysiology of unipolar depression and optimize treatments. A heuristic target for exploring the relevance of epigenetic changes in unipolar depression is the hypothalamic-pituitary-adrenal (HPA) axis. The glucocorticoid receptor (GR) gene (NR3C1) has been found to be susceptible to epigenetic modification, specifically DNA methylation, in the context of environmental stress such as early life trauma, which is an established risk for depression later in life. METHOD: In this paper we discuss the progress that has been made by studies that have investigated the relationship between depression, early trauma, the HPA axis and the NR3C1 gene. Difficulties with the design of these studies are also explored. RESULTS: Future efforts will need to comprehensively address epigenetic natural histories at the population, tissue, cell and gene levels. The complex interactions between the epigenome, genome and environment, as well as ongoing nosological difficulties, also pose significant challenges. CONCLUSIONS: The work that has been done so far is nevertheless encouraging and suggests potential mechanistic and biomarker roles for differential DNA methylation patterns in NR3C1 as well as novel therapeutic targets.

Neurocognitive intra-individual variability in mood disorders: effects on attentional response time distributions.

BACKGROUND: Attentional impairment is a core cognitive feature of major depressive disorder (MDD) and bipolar disorder (BD). However, little is known of the characteristics of response time (RT) distributions from attentional tasks. This is crucial to furthering our understanding of the profile and extent of cognitive intra-individual variability (IIV) in mood disorders. METHOD: A computerized sustained attention task was administered to 138 healthy controls and 158 patients with a mood disorder: 86 euthymic BD, 33 depressed BD and 39 medication-free MDD patients. Measures of IIV, including individual standard deviation (iSD) and coefficient of variation (CoV), were derived for each participant. Ex-Gaussian (and Vincentile) analyses were used to characterize the RT distributions into three components: mu and sigma (mean and standard deviation of the Gaussian portion of the distribution) and tau (the 'slow tail' of the distribution). RESULTS: Compared with healthy controls, iSD was increased significantly in all patient samples. Due to minimal changes in average RT, CoV was only increased significantly in BD depressed patients. Ex-Gaussian modelling indicated a significant increase in tau in euthymic BD [Cohen's d = 0.39, 95% confidence interval (CI) 0.09-0.69, p = 0.011], and both sigma (d = 0.57, 95% CI 0.07-1.05, p = 0.025) and tau (d = 1.14, 95% CI 0.60-1.64, p < 0.0001) in depressed BD. The mu parameter did not differ from controls. CONCLUSIONS: Increased cognitive variability may be a core feature of mood disorders. This is the first demonstration of differences in attentional RT distribution parameters between MDD and BD, and BD depression and euthymia. These data highlight the utility of applying measures of IIV to characterize neurocognitive variability and the great potential for future application.

Carbachol excites sublaterodorsal nucleus neurons projecting to the spinal cord.

Considerable electrophysiological and pharmacological evidence has long suggested an important role for acetylcholine in the regulation of rapid-eye-movement (REM) sleep. For example, injection of the cholinergic agonist carbachol into the dorsomedial pons produces an REM sleep-like state with muscle atonia and cortical activation, both of which are cardinal features of REM sleep. Located within this region of the pons is the sublaterodorsal nucleus (SLD), a structure thought to be both necessary and sufficient for generating REM sleep muscle atonia. Subsets of glutamatergic SLD neurons potently contribute to motor inhibition during REM sleep through descending projections to motor-related glycinergic/GABAergic neurons in the spinal cord and ventromedial medulla. Prior electrophysiological and pharmacological studies examining the effects of acetylcholine on SLD neurons have, however, produced conflicting results. In the present study, we sought to clarify how acetylcholine influences the activity of spinally projecting SLD (SLDsp) neurons. We used retrograde tracing in combination with patch-clamp recordings and recorded pre- and postsynaptic effects of carbachol on SLDsp neurons. Carbachol acted presynaptically by increasing the frequency of glutamatergic miniature excitatory postsynaptic currents. We also found that carbachol directly excited SLDsp neurons by activating an Na(+)-Ca(2+) exchanger. Both pre- and postsynaptic effects were mediated by co-activation of M1 and M3 muscarinic receptors. These observations suggest that acetylcholine produces synergistic, excitatory pre- and postsynaptic responses on SLDsp neurons that, in turn, probably serve to promote muscle atonia during REM sleep.

Somatodendritic 5-hydroxytryptamine1A (5-HT1A) autoreceptor function in major depression as assessed using the shift in electroencephalographic frequency spectrum with buspirone.

BACKGROUND: Positron emission tomography and post-mortem studies of the number of somatodendritic 5-hydroxytryptamine(1A) (5-HT(1A)) autoreceptors in raphé nuclei have found both increases and decreases in depression. However, recent genetic studies suggest they may be increased in number and/or function. The current study examined the effect of buspirone on the electroencephalographic (EEG) centroid frequency, a putative index of somatodendritic 5-HT(1A) receptor functional status, in a cohort of medication-free depressed patients and controls. METHOD: A total of 15 depressed patients (nine male) and intelligence quotient (IQ)-, gender- and age-matched healthy controls had resting EEG recorded from 29 scalp electrodes prior to and 30, 60 and 90 min after oral buspirone (30 mg) administration. The effect of buspirone on somatodendritic 5-HT(1A) receptors was assessed by calculating the EEG centroid frequency between 6 and 10.5 Hz. The effect of buspirone on postsynaptic 5-HT(1A) receptors was assessed by measuring plasma growth hormone, prolactin and cortisol concentrations. RESULTS: Analysis of variance revealed a significantly greater effect of buspirone on the EEG centroid frequency in patients compared with controls (F1,28 = 6.55, p = 0.016). There was no significant difference in the neuroendocrine responses between the two groups. CONCLUSIONS: These findings are consistent with an increase in the functional status of somatodendritic, but not postsynaptic, 5-HT1A autoreceptors, in medication-free depressed patients in line with hypotheses based on genetic data. This increase in functional status would be hypothesized to lead to an increase in serotonergic negative feedback, and hence decreased release of 5-HT at raphé projection sites, in depressed patients.

Trajectories of improvement with repetitive transcranial magnetic stimulation for treatment-resistant major depression in the BRIGhTMIND trial.

Repetitive transcranial magnetic stimulation (rTMS) is an established non-invasive brain stimulation treatment for major depressive disorder, but there is marked inter-individual variability in response. Using latent class growth analysis with session-by-session patient global impression ratings from the recently completed BRIGhTMIND trial, we identified five distinct classes of improvement trajectory during a 20-session treatment course. This included a substantial class of patients noticing delayed onset of improvement. Contrary to prior expectations, members of a class characterised by early and continued improvement showed greatest inter-session variability in stimulated location. By relating target locations and inter-session variability to a well-studied atlas, we estimated an average of 3.0 brain networks were stimulated across the treatment course in this group, compared to 1.1 in a group that reported symptom worsening (p < 0.001, d = 0.893). If confirmed, this would suggest that deliberate targeting of multiple brain networks could be beneficial to rTMS outcomes.

A naturalistic evaluation and audit database of agomelatine: clinical outcome at 12 weeks.

OBJECTIVE: To determine the effectiveness of agomelatine in routine clinical practice and explore factors associated with response and continuation. METHOD: Consecutive patients prescribed agomelatine in participating psychiatric services were included. Patient demographic and outcome data were collected at treatment initiation and then at weeks 4, 8 and 12. Outcomes were analysed with respect to clinical and demographic factors. RESULTS: A total of 110 patients from nine NHS trusts were followed through 12 weeks of treatment. Agomelatine was largely used in difficult-to-treat or refractory patients: 83 (75%) had failed to respond to, or relapsed on, prior antidepressants. There were high rates of physical (54.5%) and psychiatric (50.0%) comorbidity. At 12 weeks of treatment, 68 (62%) continued agomelatine treatment. Overall, 69 subjects (62.7%) improved by at least one point of the Clinical Global Impression (severity) scale. Of 42 who discontinued, 23 (56%) discontinued because of lack of efficacy and 10 (24%) due to an adverse event. Of all variables examined, only a history of more than five episodes of depression significantly predicted discontinuation of treatment (OR continuation - 0.36, 95% CI 0.14, 0.95). CONCLUSION: Agomelatine was effective and generally well tolerated in a cohort of difficult-to-treat patients in clinical practice.

The use of antidepressants in clinical practice: focus on agomelatine.

OBJECTIVE: Agomelatine (Valdoxan) is licensed by the European Medicines Agency for the treatment of major depressive episodes in adults. The objective of this review was to consider how the drug should be used in clinical practice in particular starting, stopping and switching to and from the drug. METHODS: The existing clinical evidence was reviewed. RESULTS: Data suggest that when switching to agomelatine from other antidepressants consideration should be given to tapering the previous antidepressant in order to minimize the risk of the original drug causing discontinuation/withdrawal symptoms. The risk of pharmacological interactions between most antidepressants and agomelatine is low and so tapering the previous antidepressant can usually be done after agomelatine has been started. An exception is fluvoxamine which should not be concurrently prescribed with agomelatine. As agomelatine appears to cause no significant discontinuation symptoms, it can probably be stopped abruptly when treatment is completed or when switching to another antidepressant. CONCLUSIONS: While this guidance may change as clinical evidence and experience grows, currently agomelatine appears to have a good tolerability profile and is relatively easy to use, though prescribers should note the requirement to conduct liver function tests (LFTs) in accordance with the Summary of Product Characteristics (SPC).

The identification, assessment and management of difficult-to-treat depression: An international consensus statement.

BACKGROUND: Many depressed patients are not able to achieve or sustain symptom remission despite serial treatment trials - often termed "treatment resistant depression". A broader, perhaps more empathic concept of "difficult-to-treat depression" (DTD) was considered. METHODS: A consensus group discussed the definition, clinical recognition, assessment and management implications of the DTD heuristic. RESULTS: The group proposed that DTD be defined as "depression that continues to cause significant burden despite usual treatment efforts". All depression management should include a thorough initial assessment. When DTD is recognized, a regular reassessment that employs a multi-dimensional framework to identify addressable barriers to successful treatment (including patient-, illness- and treatment-related factors) is advised, along with specific recommendations for addressing these factors. The emphasis of treatment, in the first instance, shifts from a goal of remission to optimal symptom control, daily psychosocial functional and quality of life, based on a patient-centred approach with shared decision-making to enhance the timely consideration of all treatment options (including pharmacotherapy, psychotherapy, neurostimulation, etc.) to optimize outcomes when sustained remission is elusive. LIMITATIONS: The recommended definition and management of DTD is based largely on expert consensus. While DTD would seem to have clinical utility, its specificity and objectivity may be insufficient to define clinical populations for regulatory trial purposes, though DTD could define populations for service provision or phase 4 trials. CONCLUSIONS: DTD provides a clinically useful conceptualization that implies a search for and remediation of specific patient-, illness- and treatment obstacles to optimizing outcomes of relevance to patients.

Inhibition of insulin release by norepinephrine in man.

Normal subjects were given glucose (300 mg/ min) or tolbutamide (1 g, intravenously), alone and during intravenous infusions of norepi-nephrine (6 lg/ min). Immunoreactive insulin concentration was less than expected during the infusions of norepinephrine, but returned to higher values after the norepinephrine infusions. From these data it is concluded that norepinephrine inhibits the release of insulin from pancreatic beta cells.

Fission power: an evolutionary strategy.

Motivated by concerns about the difficulty of safeguarding the large flows of plutonium in a breeder reactor fuel cycle, we explore the resource and economic implications of a strategy in which there is no nuclear weapons-usable material in fresh reactor fuel. The strategy involves the deployment of already developed types of advanced converter reactors which, unlike the breeder, can be operated effectively on proliferation-resistant once-through fuel cycles. Advanced converter reactors could be much more uranium-efficient on once-through fuel cycles than current systems and therefore could compete economically with breeders up to very high uranium prices. If necessary, the uranium requirements of an advanced converter reactor system could be reduced much further with the recycling of isotopically denatured uranium, but any commitment to a closed fuel cycle would be unnecessary for many decades.

Evidence for high levels of vertical transmission in Toxoplasma gondii.

Toxoplasma gondii is a highly ubiquitous and prevalent parasite. Despite the cat being the only definitive host, it is found in almost all geographical areas and warm blooded animals. Three routes of transmission are recognised: ingestion of oocysts shed by the cat, carnivory and congenital transmission. In natural populations, it is difficult to establish the relative importance of these routes. This paper reviews recent work in our laboratory which suggests that congenital transmission may be much more important than previously thought. Using PCR detection of the parasite, studies in sheep show that congenital transmission may occur in as many as 66% of pregnancies. Furthermore, in families of sheep on the same farm, exposed to the same sources of oocysts, significant divergent prevalences of Toxoplasma infection and abortion are found between different families. The data suggest that breeding from infected ewes increases the risk of subsequent abortion and infection in lambs. Congenital transmission rates in a natural population of mice were found to be 75%. Interestingly, congenital transmission rates in humans were measured at 19.8%. The results presented in these studies differ from those of other published studies and suggest that vertical transmission may be much more important than previously thought.

Evidence-based guidelines for treating depressive disorders with antidepressants: a revision of the 2000 British Association for Psychopharmacology guidelines.

A revision of the 2000 British Association for Psychopharmacology evidence-based guidelines for treating depressive disorders with antidepressants was undertaken to incorporate new evidence and to update the recommendations where appropriate. A consensus meeting involving experts in depressive disorders and their management was held in May 2006. Key areas in treating depression were reviewed, and the strength of evidence and clinical implications were considered. The guidelines were drawn up after extensive feedback from participants and interested parties. A literature review is provided, which identifies the quality of evidence to inform the recommendations, the strength of which are based on the level of evidence. These guidelines cover the nature and detection of depressive disorders, acute treatment with antidepressant drugs, choice of drug versus alternative treatment, practical issues in prescribing and management, next-step treatment, relapse prevention, treatment of relapse, and stopping treatment.

Characterization of proinsulin-insulin intermediates in human plasma.

This work addressed the problem of heterogeneity of immunoreactive insulin (IRI) in human plasma. Subjects with normal glucose tolerance were given 75g of an oral glucose solution, followed in 30 min by an intravenous infusion of 30g of arginine over 30 min. At the end of the infusion blood was withdrawn for analysis. IRI was extracted from plasma of individual subject by immunosorbent columns and was fractionated by gel filtration, disc gel electrophoresis and isoelectric focusing. Human IRI components were identified by molecular size, immunoreactivity with a human proinsulin antibody, sensitivity to trypsin, and by comparison of electrophoretic mobility and isoelectric point with porcine pancreatic products, after suitable correction for electric charge and molecular weight differences. The pattern of IRI heterogeneity was the same among six healthy subjects. Heterogeneity of proinsulin-size IRI in circulation was more marked than that of insulin-size material. Proinsulin and desdipeptide proinsulin were present in approximately equal amounts accompanied by minor amounts of split proinsulin and monodesamido-desdipeptide proinsulin. Insulin-size IRI contained over 80% insulin. Minor amounts of monodesamidoinsulin and diarginylinsulin were observed in some cases. The types of IRI components observed in plasma are evidence in support of a physiologic role of trypsin-and carboxypeptidase B-like enzymes in the conversion of proinsulin to insulin. Moreover, this study provides a base line for investigation of abnormalities in proinsulin-to-insulin conversion that may be associated with certain pathologic states.

The nature of human serum insulin-like activity (ILA)P Characterization of ILA in serum and serum fractions obtained by acid-ethanol extraction and adsorption chromatography.

Studies were undertaken in an attempt to clarify the apparent heterogeneous nature of human serum insulin-like activity. Methods of preparative zone electrophoresis on Pevikon, acid-ethanol extraction of trichloroacetic acid serum protein precipitates, adsorption chromatography on DEAE-cellulose and Dowex 50, gel filtration chromatography, and insulin antiserum immunoreactivity were used. The results establish the presence of a substance in serum with in vitro biological properties similar to insuln but with different physicochemical properties. The major portion of serum ILA measured by bioassay techniques can be attributed to the effects of this substance. Whereas the in vitro biological effects of this substance on muscle and adipose cells were similar to those of crystalline insulin, the substance is distinguished from insulin by: (1) the failure of insulin antiserum to inhibit its in vitro biological effect; (2) a slower electrophoretic mobility (in the gamma-beta globulin zone); and (3) a larger molecular weight, between 40,000 and 50,000 in these studies. It is similar to insulin since both are soluble in acid-ethanol. The results further indicate that previously described insulin-like activity in gamma-beta globulin preparations, the major portion of total serum insulin activity described in acid-ethanol extracts of serum, "bound" insulin, "atypical" insulin, and antibody nonsuppressible insulin-like activity bioassayed in diluted serum are all one and the same substance.